An AXA mounted retractable tool bit holder allows me to quickly pull the cutter
back at the end of the
thread, keep the lead screw half-nut engaged, & only advance the compound into
the workpiece. Used
with the updated variable-speed DC
motor drive, single-point threading
is now much easier & precise.
The Hardinge HLV-H has
a built-in tool bit retraction mechanism with the lever on top of the compound.

Modular Tool HolderThe steel tool
holder is modular so different plates can be designed to hold many different bit
types
including
square-shank & inside threading bars. A solid carbide bit is shown. Two, 10-24
full dog-pointset screws
hold
the 3/16" (0.1875" or 4.7625mm) tool bit. Five, 8-32 bolts secure the plate to the base.

It was quick to determine the detent locations. I assembled
it, moved the knob through its range several
times, then disassembled it, punched the ends of the mark & drilled. Produces a
clean, positive click.

The slot must be the exact same width of the bronze cam &
one
radius distance above
the
centerline for it to properly stop at the two extreme (about a 170 degrees) detent
positions.
If the slot is rotated 180 degrees, the lever will move in the opposite
direction of the cutter.
Having a bronze cam moving against a steel part is smooth & should wear well
over time.
During assembly, the dovetails, cam shaft, & ball detent were lightly lubricated
with grease.